Japanese Unexamined Patent Application Publication No. 2015-92641 describes a technique relating to a photo-detection device that electrically couples a monocrystalline n-type Ge material and an electrode via a germanide region.
Japanese Unexamined Patent Application Publication No. 2013-207231 describes a technique for reducing a current leak by forming a Si protective film over a Ge layer. In this technique, silicon (Si) is fully joined as a nickel silicide layer (NiSi) to a NiGe layer in a region where the Si protective film is in contact with a metallic layer, thereby reducing a contact resistance. The nickel silicide layer (NiSi) is a mixed crystal layer containing nickel (Ni).
Japanese Unexamined Patent Application Publication No. 2012-124483 describes a technique for reducing a contact resistance by forming electrodes on an n-type Ge region with an interfacial silicon layer doped with an n-type impurity between the electrodes and the n-type Ge region.